The camera is scaled like this and the render image is also stretched'
There is no such thing as &quot;for some reason&quot; the only reason is because you changed settings, without knowing what they are for.
Do you know what the aspect X and aspect Y controls do?
If you don't, then don't touch them. Set them back to 1.
Also, moving the scale for the camera in the 3d vieport will only affect how big it looks on the viewport, but will have no effect on the render whatsoever.
I suspect you wanted to change the field of view of the camera, as in the zoom lens of a camera, if so, then change (and animate) the lens size (focal length).

To understand what the aspect controls are for read:
Rendered aspect ratio different from the viewport&#39;s camera view